U.S. patent number 6,309,178 [Application Number 09/400,736] was granted by the patent office on 2001-10-30 for downstream guiding device for fan-radiator cooling system.
Invention is credited to William F. Gevers, Young S. Kim, Constantine Xykis.
United States Patent |
6,309,178 |
Kim , et al. |
October 30, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Downstream guiding device for fan-radiator cooling system
Abstract
A guiding device for use with a fan-radiator cooling system
wherein the fan is upstream from the radiator. The guiding device
comprises a series of guide vanes in combination with at least one
guide ring. When placed between the fan and the radiator, the
device improves the heat transfer capacity of the cooling system by
directing air flow through the radiator center, a region that
typically suffers from reduced flow due to the air flow pattern in
and around the fan hub. Furthermore, the guide vanes align the air
flow from the fan so that it is generally parallel with the axis of
the fan. The guiding device permits greater heat removal with a
given fan and radiator without increasing the speed of the fan.
Inventors: |
Kim; Young S. (Fridley, MN),
Gevers; William F. (White Bear Lake, MN), Xykis;
Constantine (Eagan, MN) |
Family
ID: |
23584798 |
Appl.
No.: |
09/400,736 |
Filed: |
September 22, 1999 |
Current U.S.
Class: |
415/176;
415/208.2; 415/211.2 |
Current CPC
Class: |
F01P
11/10 (20130101); F04D 29/582 (20130101); F04D
29/544 (20130101) |
Current International
Class: |
F01P
11/10 (20060101); F04D 29/58 (20060101); F04D
29/40 (20060101); F04D 29/54 (20060101); F04D
029/58 () |
Field of
Search: |
;415/211.2,208.2,210.1,191,192,176,220 ;416/189,192,169A
;165/DIG.311,DIG.316,DIG.317 ;290/1B ;123/41.49,41.65 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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4305928 |
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Sep 1994 |
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DE |
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19804255 |
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Aug 1999 |
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DE |
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0761982 |
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Mar 1997 |
|
EP |
|
2772844 |
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Jun 1999 |
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FR |
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Other References
"Axial Flow Fans", Library of Congress Cataloguing-in-Publication
Data, 4.18-4.21, (1998). .
"Fans Axial Flow", Genium Publishing, 7-8, (Apr., 1983). .
Lakshminarayana, B., "Fluid Dynamics and Heat Transfer of
Turbomachinery.", Library of congress Cataloguing-in-Publication
Data, A Wiley-Interscience Publication, 3 pp., (1996). .
Lewis, R.I., "Turbomachinery Performance Analysis", Library of
Congress Cataloguing-in-Publication, 1 p., (1996)..
|
Primary Examiner: Look; Edward K.
Assistant Examiner: Nguyen; Ninh
Attorney, Agent or Firm: Schwegman, Lundberg, Woessner &
Kluth, P.A.
Claims
What is claimed is:
1. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator.
2. The device of claim 1 further comprising a supplemental ring
coaxial with the guide ring and proximal the second, outer
diameter.
3. The device of claim 1 wherein the guide ring further defines a
second axis substantially coaxial with the first axis.
4. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator,
wherein the guide vanes comprise a first plurality of outer guide
vanes and a second plurality of inner guide vanes.
5. The device of claim 4 wherein the outer guide vanes extend
outwardly from the guide ring and the inner guide vanes extend
inwardly from the guide ring.
6. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator,
wherein the guide ring has an entrance diameter for receiving the
air flow from the fan and an exit diameter for delivering the air
flow to the radiator, wherein the entrance diameter is larger than
the exit diameter.
7. The device of claim 6 wherein the guide ring further comprises a
diverging region medial to the entrance and exit diameters, the
diverging region having an expansion diameter wherein the expansion
diameter is larger than the entrance and exit diameters.
8. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator,
wherein the guide ring is located such that the average volumetric
flow rate per unit area outside the guide ring is approximately
equal to the average volumetric flow rate per unit area inside the
guide ring.
9. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator,
wherein the guide vanes have a leading edge generally parallel to
the air flow entering the device and a trailing edge adapted to
deliver the air flow generally parallel to the first axis.
10. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator;
and
a supplemental ring coaxial with the guide ring and proximal the
first, inner diameter.
11. A device to control air flow between a fan and a radiator in a
fan-radiator cooling system, the device comprising:
a plurality of guide vanes that radiate outwardly about a first
axis from a first, inner diameter to a second, outer diameter;
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward an inactive region of the radiator;
and
a first supplemental ring coaxial with the guide ring and proximal
the second, outer diameter and a second supplemental ring also
coaxial with the guide ring and proximal the first, inner
diameter.
12. A fan-radiator cooling system comprising:
an axial fan having a plurality of fan blades emanating from a
central hub wherein the central hub has a hub diameter and the fan
blades define a blade diameter;
a radiator downstream and spaced apart from the axial fan; and
a guiding device between the axial fan and the radiator, the device
comprising:
a plurality of stationary guide vanes that radiate outwardly about
a first axis from a first, inner diameter to a second, outer
diameter; and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward a center region of the radiator, the
guide ring defining a second axis substantially coaxial with the
first axis.
13. The system of claim 12 wherein the first diameter is larger
than the hub diameter.
14. The system of claim 12 wherein the second diameter is equal to
or larger than the blade diameter.
15. The system of claim 12 further comprising a tubular duct
spanning between the fan and the radiator, the duct adapted to
contain air flowing between the fan and the radiator.
16. A fan-radiator cooling system comprising:
an axial fan having a plurality of fan blades emanating from a
central hub wherein the central hub has a hub diameter and the fan
blades define a blade diameter;
a radiator downstream and spaced apart from the axial fan; and
a guiding device between the axial fan and the radiator, the device
comprising:
a plurality of stationary guide vanes that radiate outwardly about
a first axis from a first, inner diameter to a second, outer
diameter; and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward a center region of the radiator, the
guide ring defining a second axis substantially coaxial with the
first axis, wherein the guide vanes have a leading edge generally
aligned with the air flow generated by the fan and a trailing edge
aligned to direct the air flow generally perpendicular to the
radiator.
17. A fan-radiator cooling system comprising:
an axial fan having a plurality of fan blades emanating from a
central hub wherein the central hub has a hub diameter and the fan
blades define a blade diameter;
a radiator downstream and spaced apart from the axial fan; and
a guiding device between the axial fan and the radiator, the device
comprising:
a plurality of stationary guide vanes that radiate outwardly about
a first axis from a first, inner diameter to a second, outer
diameter; and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward a center region of the radiator, the
guide ring defining a second axis substantially coaxial with the
first axis, wherein the guide ring is located intermediate to the
first diameter and the second diameter.
18. A fan-radiator cooling system comprising:
an axial fan having a plurality of fan blades emanating from a
central hub wherein the central hub has a hub diameter and the fan
blades define a blade diameter;
a radiator downstream and spaced apart from the axial fan; and
a guiding device between the axial fan and the radiator, the device
comprising:
a plurality of stationary guide vanes that radiate outwardly about
a first axis from a first, inner diameter to a second outer
diameter; and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward a center region of the radiator, the
guide ring defining a second axis substantially coaxial with the
first axis, wherein the guide vanes comprise a first plurality of
outer guide vanes and a second plurality of inner guide vanes.
19. A generator set comprising:
a heat-producing prime mover;
a converting apparatus that converts work output of the prime mover
into electrical energy; and
a cooling system for removing heat generated by the prime mover,
the cooling system comprising:
an axial fan having a plurality of fan blades emanating from a
central hub;
a radiator downstream and spaced apart from the axial fan; and
a guiding device between the axial fan and the radiator, the device
comprising:
a plurality of stationary guide vanes that radiate outwardly about
a first axis from a first, inner diameter to a second, outer
diameter; and
a generally annular guide ring coupled to the guide vanes, wherein
the guide ring is adapted to direct a portion of the air flowing
through the device toward a center region of the radiator, the
guide ring defining a second axis substantially coaxial with the
first axis.
20. A method for using an axial fan to push air through a radiator,
the method comprising:
providing a cooling system comprising:
an axial fan, the fan having a plurality of blades coupled to a
rotating hub, the hub adapted to selectively receive power from a
power source;
a radiator positioned generally perpendicular to an axis of the
axial fan and located downstream therefrom; and
a guiding device intermediate the fan and radiator;
generating air flow by selectively engaging the power source to
rotate the fan blades; and
directing the air flow with the guiding device so that a portion of
the flow is directed to a center region of the radiator.
21. The method of claim 20 further comprising redirecting non-axial
flow produced by the fan in a direction perpendicular to the
radiator.
Description
TECHNICAL FIELD
This invention relates generally to cooling systems and, more
particularly, to a guiding device for use with a fan-radiator
cooling system wherein the radiator is positioned downstream from
the fan.
BACKGROUND OF THE INVENTION
Cooling systems capable of removing a heat load from a
heat-producing source are well known. For modest loads, a forced
air system is often adequate. Forced air systems typically utilize
an axial or centrifugal fan to pull or push air across the
heat-producing source. For more substantial heat loads such as
internal combustion engines, a liquid coolant heat exchanger or
"radiator" may be used in conjunction with the fan.
The fan typically comprises a series of fan blades coupled to a
spinning hub and positioned to direct ambient air flow over the
radiator. The radiator comprises a plurality of tubes which are
oriented generally normal to the fan axis. Each tube includes a
series of fins to increase its surface area (and thus its heat
transfer capacity). A liquid coolant is circulated through the
heat-producing source wherein it absorbs heat energy. The coolant
then passes through the radiator tubes, transferring heat energy
through the tubes and fins to the ambient air flowing through the
radiator. The cooled liquid is then routed back through the
heat-producing source where it is once again heated. Accordingly,
heat energy is continuously removed by the liquid coolant and
transferred to the moving air.
Generally speaking, fan-radiator cooling systems can be classified
based on the direction of air flow. In "pull" systems, the fan is
positioned downstream from the radiator wherein it draws or pulls
air therethrough. Pull systems are commonly found on motor vehicles
such as automobiles and on some industrial cooling systems.
Fan-radiator cooling systems may also be configured as "push"
systems. As the name implies, push systems position the fan
upstream from the radiator where the fan exhausts or pushes air
through the radiator. Push-type systems are often selected based on
packaging or installation limitations or where it is desirable to
have cooler air passing over the fan. The present invention is
directed to push-type systems and the remainder of the discussion
will focus accordingly.
While push-type fan-radiator systems are effective heat exchangers,
problems nevertheless remain. One problem is related to the flow
characteristics of the axial fan. In particular, the output of an
axial fan is not entirely axial but rather helical. The resulting
flow thus has both an axial and a circumferential component. Since
the circumferential flow component is not aligned with the tubes
and fins of the radiator (i.e., it is not normal to the radiator
surface), it contributes little to cooling. Rather, this
circumferential flow increases entrance loss into the radiator,
degrading overall efficiency.
Yet another problem with these systems is caused by the fan hub.
Specifically, since the fan blades do not extend inwardly past the
hub, the fan is unable to efficiently generate air flow into the
region of the radiator that is aligned with the hub. Accordingly, a
lower volumetric flow rate exists in and around the radiator center
region. Stated alternatively, an inactive zone is produced in the
radiator center wherein coolant flowing therethrough is unable to
transfer the same amount of heat energy as coolant flowing
elsewhere through the radiator. Thus, the overall heat removal
capacity of the radiator is reduced. Depending on such factors as
hub size, fan/radiator spacing and fan speed, the effect of the
inactive zone on heat removal may be substantial.
While not known for use with fan-radiator systems, downstream guide
vanes are often used with axial compressors and the like to address
the problem of flow alignment. Downstream guide vanes collect air
discharged by the compressor and redirect it in a generally axial
direction. Unfortunately, these guide vanes do nothing to address
the reduced flow through the inactive zone as discussed above.
Another means to increase volumetric flow is to increase the size
of the radiator and fan or, alternatively, increase the fan speed.
While these solutions improve overall heat transfer, they are
disadvantageous in terms of cost, size and power requirements. In
addition, they too do not address the issue of flow in the inactive
zone.
Thus, there are unresolved issues with current fan-radiator cooling
systems. What is needed is a push-type fan-radiator system that
provides uniform, axial air flow through the radiator and, in
particular, provides improved flow to the portion of the radiator
located directly downstream from the fan hub. What is further
needed is a system that can provide this uniform flow while
minimizing pressure loss.
SUMMARY OF THE INVENTION
A device to control air flow between a fan and a radiator in a
fan-radiator cooling system is provided comprising a plurality of
guide vanes that radiate outwardly about a first axis from a first,
inner diameter to a second, outer diameter. The device further
includes a generally annular guide ring coupled to the guide vanes,
wherein the guide ring is adapted to direct a portion of the air
flowing through the device toward an inactive region of the
radiator.
A method for using an axial fan to push air through a radiator is
also provided. The method comprises providing a cooling system
having an axial fan. The fan has a plurality of blades coupled to a
rotating hub wherein the hub is adapted to selectively receive
power from a power source. The system further includes a radiator
positioned generally perpendicular to an axis of the axial fan and
located downstream therefrom, and a guiding device intermediate the
fan and radiator. The method also includes generating air flow by
selectively engaging the power source to rotate the fan blades and
directing the air flow with the guiding device so that a portion of
the flow is directed to a center region of the radiator.
In another embodiment, a fan-radiator cooling system is provided
including an axial fan having a plurality of fan blades emanating
from a central hub wherein the central hub has a hub diameter and
the fan blades define a blade diameter. The system further includes
a radiator downstream and spaced apart from the axial fan and a
guiding device between the axial fan and the radiator. The device
includes a plurality of stationary guide vanes that radiate
outwardly about a first axis from a first, inner diameter to a
second, outer diameter; and a generally annular guide ring coupled
to the guide vanes. The guide ring is adapted to direct a portion
of the air flowing through the device toward a center region of the
radiator, the guide ring defining a second axis substantially
coaxial with the first axis.
In yet another embodiment, a generator set is provided which
includes a heat-producing prime mover; a converting apparatus that
converts work output of the prime mover into electrical energy; and
a cooling system for removing heat generated by the prime mover.
The cooling system includes an axial fan having a plurality of fan
blades emanating from a central hub. Also included is a radiator
downstream and spaced apart from the axial fan and a guiding device
between the axial fan and the radiator. The guiding device is
comprised of a plurality of stationary guide vanes that radiate
outwardly about a first axis from a first, inner diameter to a
second, outer diameter; and a generally annular guide ring coupled
to the guide vanes, wherein the guide ring is adapted to direct a
portion of the air flowing through the device toward a center
region of the radiator, the guide ring defining a second axis
substantially coaxial with the first axis.
Advantageously, the present invention provides an improved
fan-radiator cooling system. By sitting between the fan and
radiator, the guiding device of the present invention allows more
uniform flow through the radiator by redirecting a portion of the
flow to the radiator center. Accordingly, inefficiencies
attributable to reduced flow through the radiator center are
minimized or eliminated. Thus, a given heat load can be removed
with a smaller fan and radiator than would otherwise be required.
In addition, the guiding device redirects non-axial flow so that it
is generally parallel with the fan axis, thus providing smoother
flow through the radiator. Smoother flow equates with reduced
entrance loss, which in turn, permits higher volumetric flow. The
redirection of flow also results in a conversion of kinetic (i.e.,
velocity) energy into static pressure, which also contributes to
increased air flow through the radiator. Thus, the overall
efficiency of the cooling system is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention described herein will be further characterized with
reference to the drawings, wherein:
FIG. 1 is a diagrammatic perspective view of a generic generator
set having a cooling system in accordance with one embodiment of
the invention;
FIG. 2 is an diagrammatic, exploded perspective view of a
fan-radiator cooling system in accordance with one embodiment of
the present invention;
FIG. 3 is an enlarged view of a portion of the radiator of FIG.
2;
FIG. 4 is a perspective view of a guiding device for use with a
fan-radiator cooling system in accordance with one embodiment of
the invention;
FIG. 5 is a front elevation view of the guiding device of FIG.
4;
FIG. 6 is a section view of the guiding device of FIG. 5 taken
along lines 6--6 of FIG. 5;
FIG. 7 is a diagrammatic perspective view of a fan-radiator cooling
system in accordance with another embodiment of the present
invention;
FIG. 8 is a diagrammatic side elevation view of a fan-radiator
cooling system in accordance with another embodiment of the present
invention; and
FIG. 9 is a front elevation view of a guiding device in accordance
with another embodiment of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
In the following detailed description of the embodiments, reference
is made to the accompanying drawings which form a part hereof, and
in which are shown by way of illustration specific embodiments in
which the invention may be practiced. It is to be understood that
other embodiments may be utilized and structural changes may be
made without departing from the scope of the present invention.
Generally speaking, the instant invention is directed to a
push-type fan-radiator cooling system. In particular, the invention
is directed to a guiding device for guiding the flow of air from
the fan and uniformly distributing it over the entire radiator face
including the radiator center region. The radiator center typically
experiences reduced air flow in push-type systems. This is
primarily due to the fact that the flow-producing blades do not
extend into the hub region. As such, a region of reduced flow
exists directly downstream (i.e., axially aligned) from the fan hub
near the radiator center. Because the air flow is reduced, the
ability of the radiator to transfer heat from this region is also
diminished. The area affected by this reduced flow will hereinafter
be referred to, for lack of a better term, as the inactive region
or zone. Since the inactive zone has diminished capacity to
transfer heat, overall heat transfer capacity of the cooling system
is likewise decreased. To counteract this problem, fan engineers
have generally had to provide larger fans and/or larger radiators
to remove a given heat load.
The present invention permits diversion of a portion of the
fan-generated air flow to the center of the radiator, increasing
the volumetric flow rate in the inactive zone and thus improving
the heat transfer capacity of the radiator through that region.
While the invention may be utilized in most any system requiring a
push-type cooling system, the inventors perceive one particularly
advantageous application is with generator sets and the remainder
of this discussion will address the same.
With this brief introduction, attention will now be focused on
exemplary embodiments of the invention. While the embodiments that
follow are described in sufficient detail to enable one skilled in
the art to make and use the invention, the reader is reminded that
they are nonetheless exemplary and, as such, are not intended to
limit the scope of the invention in any way.
Referring first to FIG. 1, a generator set 50 is illustrated having
a cooling system 10 therein. The generator set includes a
converting apparatus 51 which converts mechanical work done by a
prime mover--such as a internal combustion engine 54--into
electrical energy. Generators sets are used for various purposes
such as emergency backups and as remote power supplies to name a
few.
Referring now to FIG. 2, the cooling system 10 is shown in an
exploded perspective view. The system, in one embodiment, comprises
a guiding device 100, a fan assembly 200 and a radiator or radiator
assembly 300. Although not central to the invention, the operation
of the fan and radiator assemblies will be briefly described. The
fan assembly 200 includes an axial fan 201 having a plurality of
blades 202 coupled to a central, rotating hub 204. The fan blades
202 are airfoil shaped or alternatively, generally planar. Each
blade has a distal tip 203 which defines the blade diameter. The
blades, in one embodiment, are surrounded along their distal tip
203 by a circumferential shroud 206. A power source such as an
electric motor 208 (see FIG. 8), supported by a series of radial
supports (not shown) connected to the shroud 206, is operatively
coupled to an axis of the hub 204 to selectively rotate the fan
201.
Mounted downstream of the fan assembly 200 generally perpendicular
to the fan axis is the radiator assembly 300. The radiator assembly
is a heat exchanging device used to remove heat from a
heat-producing source which, for purposes of this discussion, will
hereinafter be referred to as the internal combustion engine 54. In
operation, fluid circulated through the engine absorbs heat
therefrom. The fluid then passes through a plurality of tubes 302
(see FIG. 3) located within the body of the radiator assembly 300.
Each tube 302 has a plurality of fins 304 attached thereto. As the
fluid moves through the tubes, air is continually passed through
the radiator assembly by the fan assembly 200. By continually
moving air across the tubes and fins, beat energy is transferred
through the tube walls to the ambient air flow stream where it is
carried away and dispersed to the atmosphere.
The fins 304 are used to increase the surface area of the tubes 302
exposed to the passing air, thus further improving the heat
transfer capacity of the radiator assembly. After passing through
the radiator assembly, the now-cooled fluid is once again
recirculated through the engine 54. By repeatedly circulating the
fluid through the engine 54 and the radiator assembly 300, heat
energy is effectively removed from the generator set 50 (see FIG.
1). To prevent the air flow produced by the fan from exiting
circumferentially or radially, a duct 400 (removed for clarity in
FIG. 2 but shown in FIG. 8) is provided, in one embodiment, between
the downstream side of the fan and the upstream side of the
radiator. The duct generally prevents fan-generated air from
escaping to atmosphere until it has entered the radiator assembly
300.
Having described the cooling system 10 generally, attention will
now be focused on the air flow guiding device 100. When used in
conjunction with the fan assembly 200 and radiator assembly 300
described above, the guiding device 100 provides improved air flow
through the radiator assembly and more effective heat transfer from
the cooling system 10.
Referring briefly to FIGS. 2 and 4, the device 100, in one
embodiment, is a stationary component that sits between the fan
assembly 200 and radiator assembly 300. The device 100 comprises a
first plurality of outer guide vanes 102 and a second plurality of
inner guide vanes 104. The guide vanes 102, 104 extend outwardly
about a common axis to form guide surfaces. The vanes 102 and 104
are each secured to an annular guide ring 106. The device 100 is
further defined by a first side 108 located proximal the fan
assembly 200 and a second side 110 adjacent the radiator assembly
300. On the first side 108, each vane 102, 104 is defined by a
leading edge 112 while, on the second side 110, the vanes are each
defined by a trailing edge 114.
Unlike pull-type fan-radiators such as those frequently found in
automobiles, the cooling system 10 (see FIG. 2) of the present
invention positions the fan assembly 200 upstream from the radiator
assembly 300 so that air is pushed through the latter rather than
pulled. Pull-type fan systems are not prone to the problems
inherent in push-type systems as fans develop generally uniform,
axial flow (i.e., flow generally parallel to an axis of rotation of
the fan) on their upstream side. Unfortunately, the flow developed
on the downstream side of the fan is not nearly as uniform. This
problem is partially due to the orientation of the fan blades 202
relative to the axis of the fan. Since the blades are angled (or
airfoil shaped) they impart motion to the air not strictly in the
axial direction but rather in a direction normal to the blade
surface. As such, the downstream flow, while having a predominantly
axial component, also has a circumferential or rotational
component. Since only axial flow passes smoothly through the
radiator, this circumferential flow component is, undesirable.
Accordingly, one object of the guiding device 100 is to capture the
flow and redirect it in the axial direction. As such, the leading
edges 112 are generally aligned with the direction of air flow
exiting the fan while the trailing edges are generally aligned to
direct the air flow parallel to the axis of the fan ( i.e., normal
to the radiator assembly 300). In the embodiment shown in the
figures, this results in a curvilinear guide vane shape. While not
required, the inner guide vanes are shaped similar to the outer
guide vanes. The shape of the guide vanes 102, 104 permits
efficient collection and "straightening" of the air flow discharged
by the fan so that it flows generally in the axial direction. The
result is that air is passed more smoothly through the radiator. In
addition, the redirection of air flow by the vanes 102, 104 results
in a conversion of air velocity (kinetic energy) into static
pressure, which further increases the flow of air through the
radiator assembly 300.
While the guide vanes 102, 104 straighten the air flow, it is the
guide ring 106 in conjunction with the vanes that directs the air
flow to the inactive zone of the radiator assembly 300. Referring
particularly to FIGS. 5-6, the inner vanes 104 extend toward the
center to define an inner diameter 116. The particular size of the
inner diameter 116 is adapted to ensure adequate flow toward the
radiator center. The actual size depends on many factors including
the fan size, angle/shape of the fan blades and guide vanes, and
the relative location and shape of the guide ring, among others. In
a typical configuration, the fan motor 208 (see FIG. 8) is located
on the side of the fan opposite the device 100. In an alternative
embodiment where the fan motor 208 is located between the fan and
the device 100 (not shown), the inner diameter 116 is sized to
accommodate the fan hub 204 and motor 208 therein (i.e., the fan
and hub fit within the inner diameter).
In the embodiment shown in FIGS. 7 and 8, the device 100 is placed
in close proximity to the fan assembly 200 to better capture the
circumferential flow generated by the fan. Accordingly, the output
of the fan assembly 200 is more efficiently utilized. To further
increase efficiency, the device 100, in one embodiment, has an
outer diameter 128 (see FIG. 6) larger than the fan blade diameter
(i.e., the distance across the distal tips 203 of the fan 201--see
FIG. 2) to more effectively collect the air discharged proximal the
distal tip 203 of the fan 201.
Referring once again to FIG. 6, the ring 106--like the vanes 102
and 104--also includes a leading edge 118 on the first side 108 and
a trailing edge 120 on the second side 110. At the leading edge
118, the ring 106 forms an entrance diameter 122 while at the
trailing edge 120 it forms an exit diameter 124. The entrance and
exit diameters have a common axis which is generally coaxial with
the axis about which the guide vanes 102, 104 extend (and thus,
also generally coaxial with axis of the fan). In the embodiment
shown, the ring is bowed outwardly towards its center to form a
diverging region 125 having an expansion diameter 126. Accordingly,
air drawn into the entrance diameter 122 diverges or expands
momentarily into the expansion region and then converges toward the
exit diameter 124. The convergence of the ring forces air toward
the radiator center, effectively eliminating the inactive zone
experienced with conventional push-type systems. By controlling the
radial location and geometry of the ring 106, the volumetric flow
that is redirected towards the center can be controlled. In one
embodiment, the ring is located and configured such that the
average volumetric flow rate per unit area through the ring is
generally equal to the average volumetric flow rate per unit area
outside the ring. By controlling the ring size and configuration,
uniform flow over the entire radiator surface is achieved. While
the bowed ring profile minimizes pressure drop across the ring,
other ring configurations (e.g., straight taper from entrance to
exit) are also possible without departing from the scope of the
invention.
In one embodiment, the leading and trailing edges 118, 120 are
generally coplanar with the leading and trailing edges 112, 114
respectively of the vanes 102. That is, the depth of the ring 106
is approximately identical to the vane depth 129 (see FIG. 6).
However, embodiments where the ring 106 extends beyond the vanes
(in either the upstream or downstream directions) are also possible
without departing from the scope of the invention. Similarly,
embodiments where the vanes 102, 104 extend beyond the ring 106 are
also possible.
Referring now to FIG. 7, the device 100 is shown as positioned
between a diagrammatically represented fan assembly 200 and
radiator assembly 300. The general direction of air flow through
the cooling system is represented by arrows 123. FIG. 8 shows a
partial cross section of the assembled system 10. Although the
embodiment shown illustrates the motor 208 on the upstream side of
the fan, embodiments wherein the motor is located on the downstream
side are also possible within the scope of the invention.
In one embodiment, a tubular duct or shroud 400 as shown in FIG. 8
is provided. The duct 400 effectively contains air flowing between
the fan assembly 200 and the radiator assembly 300. The duct 400
spans from the downstream side of the fan assembly 200 to the
upstream side of the radiator assembly 300. By utilizing the duct
400, air entering the cooling system 10 can then generally exit the
system only after passing through the device 100 and the radiator
assembly 300. The duct includes mounting provisions for securing
the device 100 therein.
In one embodiment, the guiding device 100 comprises fifteen outer
guide vanes 102 and eight inner guide vanes 104. However, this
configuration is specific to one particular application and
embodiments utilizing differing numbers and differing
configurations of guide vanes are possible without departing from
the scope of the invention.
In addition to varying the guide vanes 102, 104, other embodiments
such as that shown in FIG. 9 are also possible. FIG. 9 shows the
device 100 with supplemental rings 130 and 132 located on the outer
diameter 128 and the inner diameter 116 respectively. These rings
are used not only to assist with flow containment and direction,
but also to provide structural support when the vanes are unusually
long or flexible. Like the ring 106, the rings 130, 132, in one
embodiment, extend beyond the first or second side 108, 110.
Nevertheless, in order to prevent interference with flow into the
inactive zone, the leading edge of the ring 132 does not extend
substantially beyond the device 100. In one embodiment, the ring
132 has a leading edge which extends beyond the first side 108 of
the device 100 a distance of no more than one third the depth 129
(see FIG. 6).
Advantageously, the present invention provides an improved
fan-radiator cooling system. By sitting between the fan and
radiator, the guiding device of the present invention allows more
uniform flow through the radiator by redirecting a portion of the
flow to the radiator center. Accordingly, inefficiencies
attributable to reduced flow through the radiator center are
minimized or eliminated. Thus, a given heat load can be removed
with a smaller fan and radiator than would otherwise be required.
In addition, the guiding device redirects non-axial flow so that it
is generally parallel with the fan axis (and thereby perpendicular
to the radiator), thus providing smoother flow through the
radiator. Smoother flow equates with reduced entrance loss, which
in turn, permits higher volumetric flow. The redirection of flow
also results in a conversion of kinetic (i.e., velocity) energy
into static pressure, which also contributes to increased air flow
through the radiator. Thus, the overall efficiency of the cooling
system is improved.
Preferred embodiments of the present invention are described above.
Those skilled in the art will recognize that many embodiments are
possible within the scope of the invention. Variations,
modifications, and combinations of the various parts and assemblies
can certainly be made and still fall within the scope of the
invention. Thus, the invention is limited only by the following
claims, and equivalents thereto.
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